Structure of the Parasporal Inclusion of Bucillus thuringiensis Berliner: Characterization of a Repetitive Subunit

The parasporal inclusion of Bacillus thuringiensis var. Berliner was solubilized by several processes. Action of denaturing and reducing agents on the crystal protein was studied and the dissolution products analyzed in three cases: (a) after treatment with mercaptoethanol and guanidine hydrochloride at pH 7,5, (b) after treatment with a reducing agent at pH 9.5 and (c) after treatment with 0.1 N and 1 N sodium hydroxide. By the first treatment, one N‐terminal and one C‐terminal amino acid were characterized whereas four N‐terminal residues appeared by the other processes performed at pH 9.5 and above pH 12. It is suggested that peptide bonds were disrupted in these latter cases. Ultracentrifugation experiments revealed the existence of only one repetitive subunit of molecular weight 80000 in the solution obtained after treatment by mercaptoethanol and guanidine hydrochloride at pH 7.5. Furthermore reassociated particles obtained from this solution were observed under phase‐contrast microscope.